Printing mechanisms, such as those used in desktop printers, use one or more print cartridges, sometimes referred to as “pens” which may shoot drops of liquid colorant, referred to generally herein as “ink,” onto a page supported on a platen. Platens typically are used in printers and may include a support surface for supporting and/or guiding a sheet of print media through a print zone of the printing mechanism. Each print cartridge has a print head with very small nozzles through which the ink drops are fired. To print an image, the print head typically is propelled back and forth across the media page and fires drops of ink in a desired pattern on the page. The print cartridge is usually supported in a carriage that is generally moved back and forth along a carriage rod that is positioned perpendicular to the axis of media travel.
In such printers the distance between the surface that supports the media, such as ribs on a platen, and the print head may affect printing high quality images. In general, the closer the print head is to the media, the better the image quality the printer can produce. However, if the print head gets too close to the media there is a risk that the media could contact the print head, potentially resulting in smeared output and/or damage to the print head.
In many printers today, the carriage rod is supported directly on the printer base and the ribs that support the media are separately located on a platen which is also supported by the printer base. In such a device the print head-to-media support spacing generally has large tolerances, i.e., a large variation in spacing for similarly manufactured printers, so that print head-to-media support spacing and, therefore, print quality, is not consistent printer-to-printer. Moreover, no adjustment mechanisms are provided to adjust print head-to-media spacing.
In other printers, adjustment mechanisms may be positioned between the base and the carriage rod so that the print head-to-media spacing can be adjusted during the manufacturing process to provide tight spacing control. However, adjustment of the print head-to-media spacing is generally accomplished manually; leading to higher production costs due to increased part count and assembly time and could lead to human error in adjustment of the adjustment mechanisms. Adjustment mechanisms also pose a risk that the print head-to-media spacing could move during transportation or use of the printer.